ABS/polyester blends can have good processability and excellent physical properties, such as high impact strength. Accordingly, ABS/polyester blends have been widely used in a variety of applications, including the production of internal or external parts of electric/electronic goods and office equipment. However, ABS/polyester blends can burn when used in heat-emitting devices, since ABS/polyester blends are combustable. Further, these blends can operate as an energy source to help combustion if ignited by a flame from an external heat source.
Increasingly electrical and electronic products require flame retardancy for safety reasons. Thus, methods for imparting flame retardancy to ABS/polyester blends are being developed.
However, if a large amount of flame retardant is added to a ABS/polyester blend to impart flame retardency, mold processability of the ABS/polyester blend may decrease.
Currently, electric/electronic products and office equipment are becoming larger overall, yet thinner. When ABS/polyester blends are employed in such a large, yet thin, product, it can be necessary to add a large amount of flame retardant to obtain sufficient flame retardancy. As a result, mold processability of ABS/polyester blends may decrease. Therefore, there is a need to improve flowability of ABS/polyester blends, which can directly effect mold processability of the final products.
In order to reduce the risk of a fire, halogenated flame retardants may be added to some thermoplastic resins. Halogenated flame retardants generally used include TBBPA (2,2′,6,6′-tetrabromo-4,4′-isopropylidenediphenol), tris(tribromophenoxy) triazine, decabromodiphenyl ethane (DBDPE), and the like. However, TBBPA causes an environmental problem and is easily degraded when TBBPA is processed at high temperatures due to its low thermal decomposition temperature. Moreover, TBBPA has poor compatibility with ABS/polyester blends due to a hydroxyl (—OH) group structurally present in TBBPA.
In order to address the drawbacks of the TBBPA, tris(tribromophenoxy) triazine can be used as a flame retardant. Tris(tribromophenoxy) triazine, however, is also not desirable from an environmental aspect since the tris(tribromophenoxy) triazine is produced using tribromophenol.
DBDPE has the most favorable environmental properties among the halogenated flame retardants. However, DBDPE is difficult to use in ABS/polyester blends since DBDPE has a very high melting point and poor compatibility. Additionally, DBDPE is very limited in use since the addition of DBDPE to a resin can greatly reduce impact resistant strength and decrease flowability.